The present invention relates to a vapor pressure pump for delivering a liquid into a system operating at a higher pressure or located at a higher level by action of a vapor pressure produced from a portion of the liquid to be delivered.
Many types of vapor pressure pumps have been developed in this particular field. The pressure pumps known and commercialized under the names of "acid egg" or "pulsometer" are examples thereof.
Every pump of this particular type comprises a closed reservoir fed with a liquid under the effect of gravity via an inlet valve. The pump is useful for discharging the liquid in another reservoir having an internal pressure higher than the one of the first reservoir, or being placed above it. When a predetermined level of liquid is reached in the pump, a vapor or gas pressure higher than the pressure to force back, is injected or produced into the reservoir. As a result, the liquid is expelled into an outlet pipe through an exhaust valve.
Injection or production of a gas or vapor pressure in the reservoir may be carried out in two different manners. In the former one, vapor pressure is generated and stocked in a distinct reservoir. When the predetermined level of liquid is reached, an electrical, pneumatic or mechanical mechanism actuates the opening of a flood-gate connecting the vapor reservoir to the pump. In the latter one, a float-operated heat source is disposed inside the reservoir to evaporate a portion of the liquid contained therein and raise the vapor pressure at a value sufficient to expel the liquid as soon as the level of the liquid inside the reservoir has reached the predetermined level. Such a "thermodynamic" pump is described by way of example in U.S. Pat. No. 4,227,489 to Regamey, for use in a boiler and heat exchanger system.